Prism-plate.



J. G. BROWN.

PRlSll PLATE.

(Application filed Oct, 29,. $900,)

(No Model.)

THE Nonms PETERS co. PHOTO-LTHO. msnmcwm o 2v Patented Ian. I, l90l.

a INVENTOH 5 A; A7TORNEYS UNITED STATES PATENT OFFICE.

JAMES G. BROWN, OF CLEVELAND, OHIO, ASSIGNOR OF ONE-HALF TO THE CLEVELAND WINDOW GLASS COMPANY, OF SAME PLACE.

PRISM-PLATE.

SPECIFICATION forming part of Letters Patent No. 665,170, dated January 1, 1901.

Application filed October 29, 1900. Serial No. 34,705. (No model.)

T0 to whom it may concern:

Be it known that I, J AMEs G. BROWN, a resident of Cleveland, in the county of Cuyahoga and State of Ohio, have invented certain new and useful Improvements in Prism-Plates; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it pertains to make and use the same.

My invention relates to improvements in ligh t-diffusing prism-plates.

The object of this invention is to provide a prism-plate that has a largeilluminating ca pacity and that is capable of diffusing a large volume of light next adjacent and in close proximity to the plate, as well as over a great distance from the inner or light-diffusing side *of the plate.

With this object in view the invention consists in a novel arrangement and configuration of the prism-forming or light-diffusing ribs of the plate.

In the accompanying drawings, Figure I is a view in perspective of a prism-plate embodying my invention. Figs. II and III illustrate opposite side edges of the plate.

Referring to the drawings, ct designates the plates body portion, that, as illustrated, is arranged in a vertical plane and provided upon its inner or light-diifusing side with two series of prism-forming or light-diffusing ribs. All of the ribs are parallel and on the plate illustrated extend horizontally across the plate. Each rib b of one of the series of ribs has its two sides or faces 5 and 5 curving outwardly in end elevation and converging from the plates body portion. Each rib c of the other series of ribs has its two sides or faces 6 and 7 flat and straight and converging in end elevation from the plates body portion. All the ribs project, preferably, the same distance from the body portion of the plate; but the ribs 0 of one of the series of ribs alternate with the ribs 1) of the other series of ribs. The prism-forming ribs 0 only have the capacity of refractin g light,and the rays of light emerge from the prisms at right angles or approximately right angles to the plates body portion. A prism-forming rib 0 having one of its faces at an angle of sixty degrees and its other face at an angle of eighty degrees to the body portion of the plate has given very satisfactory results.

The peculiar external contour of the ribs 1) in end elevation renders them capable of reflecting as well as refracting light. The said ribs 1) diffuse light not only at right angles to the plates body portion, but at every angle between an angle of forty-five degree and an angle of eighty degrees to the body portion. The ribs 5 consequently diffuse light in advance of andin close proximity to or through the adjacent prism c of the plate.

A prism-plate having parallel ribs Z) with their sides or faces curved outwardly, as hereinbefore described, possesses a large light-diffusing capacity, and a prism-plate having the light-refracting prism c alternating with the aforesaid light-diffusing ribs 1) is capable of diffusing a remarkably large volume of light over a long distance, as Well as downwardly and upwardly in close proximity to the plate.

What I claim is- 1. A prism-plate having two series of ribs formed upon one and the same side of the plate and extending transversely of the plate, with the ribs of one series having outwardlycurved sides or faces in end elevation and with the ribs of the other series having fiat and straight sides or faces, and with the lastmentioned ribs alternating with the ribs hav ing curved faces, substantially as and for the purpose set forth.

2. A prism plate having the following formed upon one and the same side of the plate: a series of parallel ribs 1) extending transversely of the plate and having, respectively, two sides or faces 5 and 5 curving outwardly in end elevation and converging from the plates body portion, and another series of ribs 0 parallel and alternating with the ribs of the first-mentioned series and having, respectively, two flat or straight sides or faces 6 and 7 converging from the plates body portron.

Signed by me at Cleveland, Ohio, this 17th day of October, 1900.

' JAMES G. BROIVN.

Witnesses:

C. H. Donna, A. H. PARRATT. 

